It looks like there's a final Windows 10 build rolling out that we imagine will become tomorrow's Anniversary Update (or perhaps an update that will roll out to non-Insiders soon after the Anniversary Update goes live). It's Insider Preview build 14393.10, and it's rolling out right now to the Fast Ring via Cumulative Update KB3176929.
Windows Insider chief Dona Sarkar let us know if the update via her Twitter account, as usual:
#WindowsInsiders: we have now released cummulative update 14393.10 to the Fast Ring via Windows Update
— Dona Sarkar @ #MSIgnite (@donasarkar) August 2, 2016
We don't have any details yet on what the update provides, other than our best guess that it's some final polish before the Anniversary Update starts releasing to all Windows 10 users tomorrow. Let us know in the comments if you notice anything special in this last build before the penultimate update so far starts heading to the masses.